Wide-voltage booster circuit and energy storage inverter

Abstract

The utility model relates to the technical field of energy storage inverters, in particular to a wide-voltage booster circuit and an energy storage inverter, and the wide-voltage booster circuit comprises a first-stage circuit which is connected with a battery and is used for adjusting the voltage range of an input side and reducing current ripples of the input side; the second-stage circuit is connected with the first-stage circuit and is used for boosting to bus voltage at a high transformation ratio; and the switching circuit is connected with the first-stage circuit and the second-stage circuit and is used for connecting or isolating the second-stage circuit. According to the wide-voltage booster circuit, the input ripple rate of the battery side is reduced, the input voltage range of the battery side is widened, the input voltage range is widened while current ripples are reduced, the compatibility of an inverter to a battery is improved, and the service life of the inverter is prolonged.

Description

Technical Field

[0001] The present application relates to the technical field of energy storage inverters, and in particular to a wide voltage boost circuit and an energy storage inverter. Background Art

[0002] The primary function of an energy storage inverter is to convert direct current (DC) to alternating current (AC). Energy storage devices typically store DC energy in batteries. When the grid requires AC power, the inverter converts DC to AC, achieving energy conversion and output. Energy storage batteries age over time, and the ripple current generated by the flow of energy between the battery and the busbar significantly impacts battery life.

[0003] The bus voltage of existing inverters is usually around 380V to 500V. For common buck-boost topology circuits, regardless of the DC / DC structure, high-stress switching elements and large-volume magnetic components are required to meet their buck-boost capabilities. This leads to increased circuit costs and product volume, and the ripple of the inductor in the topology circuit will also be relatively high. Summary of the Invention

[0004] In view of this, the embodiments of the present application provide a wide voltage boost circuit, an inverter and an energy storage device, aiming to solve the problem of reducing current ripple in the boost circuit while widening the voltage input range, thereby improving the inverter's compatibility with the battery and its service life.

[0005] A first aspect of an embodiment of the present application provides a wide voltage boost circuit, comprising:

[0006] The first stage circuit is connected to the battery and is used to adjust the input side voltage range and reduce the input side current ripple;

[0007] The second stage circuit is connected to the first stage circuit and is used for boosting the voltage to the bus voltage with a high transformation ratio;

[0008] The switching circuit is connected to the first-stage circuit and the second-stage circuit, and is used to connect or isolate the second-stage circuit.

[0009] In one embodiment, the switching circuit is used to connect the second-stage circuit to complete the high transformation ratio boost when the input side voltage is lower than a preset threshold value, and to isolate the second-stage circuit to directly boost the output voltage of the first-stage circuit to the bus voltage when the input side voltage is greater than or equal to the preset threshold value.

[0010] In one embodiment, a control circuit is further included, wherein the control circuit is configured to output a first control signal to control the first stage circuit, output a second control signal to control the second stage circuit, and output a third control signal to control the switching circuit.

[0011] In one embodiment, the first stage circuit includes a two-phase interleaved parallel circuit, and the preset threshold is half of the bus voltage.

[0012] In one embodiment, when the battery is in a discharging state, when the input side voltage is lower than the preset threshold, the switching circuit connects the second stage circuit to complete the boost; when the input side voltage is greater than or equal to the preset threshold, the switching circuit isolates the second stage circuit.

[0013] In one embodiment, the first-stage circuit includes a three-phase interleaved parallel circuit, and the preset threshold is two-thirds of the bus voltage.

[0014] In one embodiment, when the battery is in a discharging state, when the input side voltage is lower than the preset threshold, the switching circuit connects the second stage circuit to complete the boost; when the input side voltage is greater than or equal to the preset threshold, the switching circuit isolates the second stage circuit.

[0015] In one embodiment, the first sub-preset threshold is further included, and the first sub-preset threshold is one third of the bus voltage;

[0016] When the input side voltage is lower than the preset threshold and greater than the first sub-preset threshold, the switching circuit turns on the second stage circuit to complete the voltage boost.

[0017] In one embodiment, the first-stage circuit includes one or more Buck / Boost topologies, and the second-stage circuit includes a Buck / Boost topology; the Buck / Boost topology includes an input end, an energy storage inductor, a first switching tube, a second switching tube, and an output end, the positive electrode of the input end is connected to the first end of the energy storage inductor, the second end of the energy storage inductor is connected to the drain of the first switching tube and the source of the second switching tube, and the source of the first switching tube is connected to the input end.

[0018] A second aspect of the embodiments of the present application provides an energy storage inverter, including a battery and a wide voltage boost circuit provided by the first aspect of the embodiments of the present application.

[0019] The beneficial effects of the embodiments of the present application are: through the two-stage boost circuit topology, the first-stage circuit is connected to the battery, used to adjust the voltage range on the input side and reduce the current ripple on the output side, the second-stage circuit is connected to the first-stage circuit, and is used for high-ratio boosting to the bus voltage. The switching circuit can connect or isolate the second-stage circuit. The wide voltage boost circuit reduces the input ripple rate on the battery side and widens the input voltage range on the battery side, thereby achieving a widened input voltage range while reducing current ripple, thereby improving the inverter's compatibility with the battery and service life, and the circuit structure is simple and low-cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0021] Figure 1 A schematic diagram of the principle of a wide voltage boost circuit provided in one embodiment of the present application;

[0022] Figure 2 A schematic diagram of a wide voltage boost circuit according to another embodiment of the present application;

[0023] Figure 3 A schematic diagram of a wide voltage boost circuit according to another embodiment of the present application;

[0024] Figure 4 A schematic diagram of a wide voltage boost circuit according to another embodiment of the present application;

[0025] Figure 5 A schematic diagram of the principle of a two-phase interleaved parallel circuit used in the first-stage circuit provided in one embodiment of the present application;

[0026] Figure 6 A schematic diagram illustrating the principle of a three-phase interleaved parallel circuit used in a first-stage circuit provided in an embodiment of the present application;

[0027] Figure 7 A schematic diagram of the principle of a DC / DC circuit used in the second-stage circuit provided in one embodiment of the present application;

[0028] Figure 8 A schematic diagram of the working process of a wide voltage boost circuit provided in one embodiment of the present application;

[0029] Figure 9 This is a schematic diagram of the working process of a wide voltage boost circuit provided in another embodiment of the present application. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not intended to limit the present application.

[0031] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0032] It should be understood that the terms "length", "width", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0033] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0034] Please refer to Figure 1 As shown in the drawings, the embodiment of the present application provides a wide voltage boosting circuit, which comprises a first stage circuit 100 connected with a battery, used for adjusting the range of input side voltage Ui and reducing the current ripple of the input side, a second stage circuit 200 connected with the first stage circuit 100, used for high variable ratio boosting to bus voltage Uo, where the battery is, for example, an energy storage battery in an energy storage inverter, the output voltage of the energy storage battery is the input side voltage Ui of the present wide voltage boosting circuit, and after boosting, it is boosted to the bus voltage Uo output. A switching circuit 300 is connected with the first stage circuit 100 and the second stage circuit 200, and the switching circuit 300 is used for connecting or isolating the second stage circuit 200. Understandably, when the switching circuit 300 connects the second stage circuit 200, i.e. the second stage circuit 200 participates in the boosting, and when the switching circuit 300 isolates the second stage circuit 200, i.e. the second stage circuit 200 is isolated from the present wide voltage boosting circuit and does not participate in the boosting process.

[0035] The wide voltage boosting circuit provided by the embodiments of the present application reduces the input ripple rate of the battery side, widens the input voltage range of the battery side, widens the input voltage range while reducing the current ripple, improves the compatibility and service life of the inverter to the battery, and has a simple circuit structure and low cost.

[0036] Please refer to Figure 1 In one embodiment, the switching circuit 300 is used to connect the second stage circuit 200 to complete high-ratio voltage boosting when the input side voltage Ui is lower than the preset threshold value Ut, and is used to isolate the second stage circuit 200 to directly boost the output voltage of the first stage circuit 100 to the bus voltage Uo when the input side voltage Ui is greater than or equal to the preset threshold value Ut. The preset threshold value Ut here can be set according to actual needs.

[0037] Further, please refer to Figure 2 In one embodiment, the wide voltage boosting circuit of the present application further includes a control circuit 400, which is used to output a first control signal to control the first stage circuit 100, output a second control signal to control the second stage circuit 200, and output a third control signal to control the switching circuit 300. The control circuit 400 also has a detection function in some embodiments, which is used to detect the range of the input side voltage Ui, and can also detect the working state of the battery on the input side, such as the charging or discharging state of the battery.

[0038] Please refer to Figure 1 , Figure 2 and Figure 3 In one embodiment, the first stage circuit 100 includes a two-phase interleaved parallel circuit, and the preset threshold value Ut is half of the bus voltage Uo. The two-phase interleaved parallel circuit includes two Buck / Boost circuits, and the two Buck / Boost circuits are interleaved in parallel. Please further refer to Figure 5 , Figure 5 for the principle diagram of the two-phase interleaved parallel circuit adopted by the first stage circuit 100.

[0039] The two-phase interleaved parallel circuit can effectively reduce the input side ripple current and prolong the battery life by canceling the ripples of each other. However, the effect can be best only at a specific duty cycle D. For example, the two-phase interleaved parallel circuit, in theory, can only cancel the current ripple to 0 when the duty cycle D is fixed at a certain value. When the duty cycle D is too large or too small, the current ripple cannot be well canceled. In actual use, users may replace batteries of different voltages. Therefore, it is difficult to fix the single-stage boost-buck duty cycle D, which restricts the voltage selection range of the battery side and makes the inverter not well compatible with batteries of different voltages.

[0040] Please refer to Figure 5 As shown in the figure, according to theoretical calculation, there is a zero point in the function of the inductance current changing with the duty cycle D of the switch tube. When D=0.5, the bus voltage Uo (Uout) is twice the input battery voltage Uin (Ui), that is, Uout / Uin=1 / (1-D)=2. That is, only when the battery with half of the bus voltage Uo is used, the effect of canceling the ripple of the interleaved parallel structure can be fully played out.

[0041] Please refer to Figure 1 、 Figure 2 、 Figure 3 and Figure 5 In an embodiment, when the battery is in a discharging state, the input side voltage Ui is lower than a preset threshold value Ut, wherein Ut=Uo / 2. At this time, two-stage boost-buck needs to be performed, and the output voltage of the first-stage circuit 100 is 2*Ui. The switching circuit 300 connects the second-stage circuit 200 to complete the boost. When the input side voltage Ui is greater than or equal to the preset threshold value Ut, the switching circuit 300 isolates the second-stage circuit 200 to directly complete the boost. It can be understood that when the battery is in a charging state, the second-stage circuit 200 reduces the bus voltage Uo to 2*Ui.

[0042] Please refer to Figure 1 、 Figure 2 and Figure 4 The first-stage circuit 100 includes a three-phase interleaved parallel circuit, and the preset threshold value Ut is two-thirds of the bus voltage Uo. The three-phase interleaved parallel circuit includes three Buck / Boost circuits, and the three Buck / Boost circuits are interleaved in parallel. Please further refer to Figure 6 , Figure 6 for the principle diagram of the three-phase interleaved parallel circuit adopted by the first-stage circuit 100.

[0043] Similar to two-phase interleaved parallel circuit, three-phase interleaved parallel circuit can effectively reduce the input side ripple current and prolong the battery life by the mutual offset of multiple ripple. For the ratio function of total inductance current ripple under three-phase interleaved parallel control and direct boost-buck inductance current ripple, there are two zero points D=1 / 3 and D=2 / 3 for duty cycle D, and only at a specific duty cycle can the ripple be maximally reduced.

[0044] As shown in Figure 6 According to theoretical calculation, there are two zero points for the function of inductance current changing with switch duty cycle D in three-phase interleaved time, the preset voltage Ut is the value satisfying the duty cycle D=0.33 (D=1 / 3), the bus voltage Uo, and the input voltage Ui / (1-D)=Uo when discharging the battery, which can be obtained by substituting Ui=0.67*Uo. Therefore, the bus voltage Uo is selected as the preset voltage Ut, and the three-phase interleaved parallel topology is fully played out to offset the ripple effect.

[0045] As shown in Figure 1 , Figure 2 , Figure 4 and Figure 6 Further, in an embodiment, when the battery is in a discharging state, the input side voltage Ui is lower than the preset threshold Ut, wherein Ut=Uo / 3, at this time, two-stage boost / buck is needed, the output of the first circuit 100 is 3*Ui, and the bus voltage Uo. The control circuit 400 generates the second control signal according to the two voltages, and the second circuit 200 is connected by the switching circuit 300 to complete the boost when the battery is charged.

[0046] As shown in Figure 1 , Figure 2 , Figure 4 and Figure 6 In an embodiment, it further includes a first sub-pre-set threshold Us, which is one-third of the bus voltage Uo, Us=Uo / 3, at this time, the duty cycle D=0.67 (D=2 / 3), when the input side voltage Ui is lower than the preset threshold Ut and greater than the first sub-pre-set threshold Us, the switching circuit 300 connects the second circuit 200 to complete the boost. The output voltage of the first circuit 100 is 1.5*Ui, the switching circuit 300 connects the second circuit 200 to complete the boost, and the control circuit 400 generates the second control signal according to the two voltages.

[0047] When the input side voltage Ui is lower than the first sub-pre-set threshold Us, the switching circuit 300 connects the second circuit 200 to complete the boost, and when the battery is discharged, the output of the first circuit 100 is 3*Ui, and the bus voltage Uo. The second control signal of the second circuit 200 is generated according to the two voltages, and the second DC / DC circuit is needed to reduce the voltage to 3*Ui when charging.

[0048] Referring to Figure 3 and Figure 4 In one embodiment, the switching circuit 300 includes a switch S1, and specifically, the switch S1 can be a relay switch.

[0049] Referring to Figures 1 to 7 In one embodiment, the first-stage circuit 100 includes one or more Buck / Boost topologies, such as Figure 3 In one embodiment, the first-stage circuit 100 includes two Buck / Boost topologies. As shown in Figure 7 In one embodiment, the second-stage circuit 200 includes one Buck / Boost topology. Each Buck / Boost topology includes at least an input terminal, an energy storage inductor, a first switch tube, a second switch tube, and an output terminal. Taking the second-stage circuit 200 as an example, the positive terminal of the input terminal of the Buck / Boost topology 210 is connected to the first terminal of the energy storage inductor L11, the second terminal of the energy storage inductor L11 is connected to the drain of the first switch tube Q11 and the source of the second switch tube Q22, and the source of the first switch tube Q11 is connected to the negative terminal of the input terminal. The control circuit 400 outputs control signals to the gates of the first switch tube Q11 and the second switch tube Q22 to control the conduction or turn-off of the switch tubes, thereby achieving the duty cycle control of the Buck / Boost topology. The Buck / Boost topologies used in the first-stage circuit 100 are similar, and thus will not be described again here.

[0050] In order to better understand the working principle of the wide voltage boost circuit of the present application, the working process of the circuit will be described below. Please further refer to Figure 8 and Figure 9 . Figure 8 The working process of the first-stage circuit 100 using two-phase interleaved parallel circuits is shown in Figure 9 The working process of the first-stage circuit 100 using three-phase interleaved parallel circuits is shown in

[0051] Specifically, in one embodiment, the first-stage circuit 100 employs a two-phase interleaved parallel circuit as an example. First, the control circuit 400 can detect the direction of energy flow, i.e., the operating state of the battery or the inverter. When the battery is in a discharging state, the battery voltage U1 is obtained. When the battery voltage U1 is less than a preset voltage U, the control circuit 400 outputs a third control signal to control the switching circuit 300 to connect to the second-stage circuit 200, disconnecting switch S1. The control circuit 400 then generates a first control signal, i.e., a two-phase interleaved control signal, and a second control signal, i.e., a DC / DC control signal, to control the first-stage circuit 100 and the second-stage circuit 200 to boost the battery voltage U1, thereby achieving the battery discharge process. When the battery voltage U1 is greater than or equal to the preset voltage U, the control circuit 400 outputs a third control signal to control the switching circuit 300 to isolate the second-stage circuit 200, closing switch S1. At this point, the control circuit 400 generates a first control signal, i.e., a two-phase interleaved control signal, to directly boost the battery voltage U1. The principles in the battery charging state are similar and will not be further elaborated here.

[0052] A second aspect of the embodiments of the present application further provides an energy storage inverter, comprising a battery and the wide voltage boost circuit provided in the first aspect of the embodiments of the present application.

[0053] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. A wide voltage boost circuit, comprising: The first stage circuit is connected to the battery and is used to adjust the input side voltage range and reduce the input side current ripple; The second stage circuit is connected to the first stage circuit and is used for boosting the voltage to the bus voltage with a high transformation ratio; The switching circuit is connected to the first-stage circuit and the second-stage circuit, and is used to connect or isolate the second-stage circuit.

2. The wide voltage boost circuit according to claim 1, wherein: The switching circuit is used to connect the second-stage circuit to complete the high transformation ratio boost when the input side voltage is lower than a preset threshold value, and to isolate the second-stage circuit to directly boost the output voltage of the first-stage circuit to the bus voltage when the input side voltage is greater than or equal to the preset threshold value.

3. The wide voltage boost circuit according to claim 2, wherein: It also includes a control circuit, which is used to output a first control signal to control the first-stage circuit, output a second control signal to control the second-stage circuit, and output a third control signal to control the switching circuit.

4. The wide voltage boost circuit according to claim 2, wherein: The first-stage circuit includes a two-phase interleaved parallel circuit, and the preset threshold is half of the bus voltage.

5. The wide voltage boost circuit according to claim 4, wherein: When the battery is in a discharging state, when the input side voltage is lower than the preset threshold, the switching circuit connects the second stage circuit to complete the boost; when the input side voltage is greater than or equal to the preset threshold, the switching circuit isolates the second stage circuit.

6. The wide voltage boost circuit according to claim 2, wherein: The first-stage circuit includes a three-phase interleaved parallel circuit, and the preset threshold is two-thirds of the bus voltage.

7. The wide voltage boost circuit according to claim 5, wherein: Also includes a first sub-preset threshold, the first sub-preset threshold being one third of the bus voltage; When the input side voltage is lower than the preset threshold and greater than the first sub-preset threshold, the switching circuit turns on the second stage circuit to complete the voltage boost.

8. The wide voltage boost circuit according to claim 1, wherein: The first-stage circuit includes one or more Buck / Boost topologies, and the second-stage circuit includes a Buck / Boost topology; the Buck / Boost topology includes an input end, an energy storage inductor, a first switching tube, a second switching tube, and an output end, the positive electrode of the input end is connected to the first end of the energy storage inductor, the second end of the energy storage inductor is connected to the drain of the first switching tube and the source of the second switching tube, and the source of the first switching tube is connected to the input end.

9. An energy storage inverter, comprising a battery, characterized in that: It also includes the wide voltage boost circuit according to any one of claims 1 to 8.

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